In the magazine "Electronik", 1979, No. 26, pages 33 to 38, a system is described in which a master microprocessor transmits information to and receives information from a multiplicity of other microprocessor systems. It is an object of such a system to decrease the data handling requirements of the microprocessor by carrying out sub-programs, etc. in so-called "slave" microprocessor systems associated therewith. In such systems, data transmission takes place either in parallel over a joint bus system or serially by addition of components for converting the data words from a parallel to a serial form. If it is impossible to effect either serial or parallel transmission between the two systems, then data transmission cannot take place between them at all.